Universal telegraph repeater



April 12,1949- R. B'. HEARN E-rAL 2,466,891

UNIVERSAL TELEGRAPH RPEATER Filed July 4, 1945 8 Sheets-Sheet 1- ATTORNVum .E .RS www:

8 Sheets-Sheet 2 A April 12, 1949. R. B. HEARN Erm.

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pri 12, 1949, R. B. HEARN ETAL 2,466,891

` UNIVERSAL TELEGRAPH REPEATER Filed July 4, 1945 a Smets-sheet s FIG. 3

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POLAR/Z50 POLAR/ED ,fea/#EARN Nl/EN TORS C. 5. Sun/FF April 12, 1949. R.B. HEARN ErAl. 2,466,891

UNIVERSAL TELEGRAPH REPEATER l Filed July 4, 1945 v a sheets-sheet 4 BVya s. @w46 A TTOR/VEV April 12, 1949. R. B. HEARN ETAL- 2,465,891

UNIVERSAL TELEGRAPH REPEATER Filed July 4, 1945 l 8 Sheets-Sheet 5 LYNEl' POWER SUPPLY Tf@ WAL usr wesr A TTOR/VEV April l2, 1949.

Filed July 4, 1945 R. B. HEARN E-rAL UNIVERSAL TELEGRAPH REPEATER L mf IPOLAR/zen 8 Sheets-Sheet 6 BREAK ND POLAR/zen l I H06' anc-c.

A TT ORNE Y April 12, 1949. R. B. HEARN ETAL UNIVERSAL TELEGRAPH REPATERFiled July 4, 1945 F1957" HEPEA TER POI. A R/ZED POLAR/Z50 8Sheets-Sheet 7 POL A l?! OLA /ZE POLAR/25D P l D F/G. /4 I /A/I/ENTORSR. B. HEAR/V By c. 5. sun /FF JM 6.9M

ATTORA/EV Patented Apr. 12, 1949 UNITED Meur oFFIcE l UNIVERSALTELEGRAPH REPEATER Richard B. Hearn, Hollis, N. Y., and Carleton B.Sutlii, East Grange, N. J., assignors to Bell Telephone Laboratories,

Incorporated, New

This-invention relates to telegraph repeaters and,y particularly yto animproved repeater for rquickly furnishing service at a terminal or at anintermediate pointunder a wide variety of conditions such as may beencountered in military service.

An object of this invention is the improvement -of telegraph repeatersystems. Amore particular vobject of the invention is the provision of arefpeater which is adaptable to a Wide variety of serviceconditionswitha minimum of adjustment. :Anotherobject-of the inventionis the provision of; a, repeater which will function on a longer span-or on a line of higher capacity than any heretofore devised Withoutkickoff of the repeater relay.

:The'repeater herein is designed to be controlled Vby manually operableswitches on its line side and on its local side so thatit can beinstantly con- VLnected-to function in alnumber of different manners andwith a number of different connecting vfacilities at different `times tomeet different i'leld conditions.

' The repeater herein is designed to provide satis- "factory serviceover' simplexed field Wire over a span of seventy-five miles whenconnected to such ra repeater as is disclosed in R. B. Hearn, C. B.lSutliff Patentv 2,422,677, issued. June 24, 1947.

When two repeaters such as are disclosed here-in areY connected togetherback to back and operatying over sirmpleXecl field wire, the system Willprofvide satisfactory service over tWc forty-mile spans. Therepeaterherein is arranged to perform the following functions.

Y1. It will operate .as a type Bpolar sending polarenti'al repeater to asimplexed eld Wire line or to a composited open Wire line;

.`2.Itfwill operate as. a type B polar receiving repeater, on simplexed-eldwire lines or composited open Wire lines;

It will operate as a two-path polar repeater fon." field telegraphcircuits;

ltfinay: be terminated directly in a printer;

' 5.' Itmay be terminated in a switchboard;

6. It may be terminated in a carrier terminal;

."'7.Tivo repeaters such as are disclosed herein "mayf-be'directlyinterconnected for operation as aa"-th`rough typeV repeater withprovision for con- V-n'e'cting'to a printerat the through point;

"'fSffItimay be connected to an electronic regen- AAerative repeatersuch as is disclosed in copending 'fapplication SerialNo. 556,352, R. B.Hearn, J.` A, Krecekfled September 29,` 1944.

GENERAL PRELIMINARY DESCRIPTION rilhe repeater herein is designatedtofacilitate rapid installation and line up for service. This isespecially desirable when the repeaterrisused for military service in'they field. To promote rapid installation and line up, the adjustablefeatures have been reduced toa minimum. This particularly-to the linesinterconnecting-the;sta-

tions in Fig. l thereof andthe associated description `Both ofthese'portions of these patents are made part of this disclosure asthough' fully Aset forth herein. "In general, the term Polarential willbe used hereinafter as signifying "type B polarential.

When the repeater herein is arranged-for'type B polarential operation,polar sending, the transmission from the polar sending end is polar,that is, the marking signal and spacing signal conditions are effectedthrough reversals of` polarity of voltages of equal magnitudes.Positive-and negative volts have been found desirable' -for use in thisparticular embodiment. Negative 75- volt potential is applied to theline -for marking and positive 75 volts for spacing. Theloperation inthe opposite directionis differential. Ground isreonnected to the linefor marking'andvv inzthis embodiment positive volts are applied forspacing. In this particular-embodiment thefcircuit is adjusted to obtainan `l-milliampere-line curent'during the marking period when signalingin eitherdirection. When transmitting from the polar sending end, theline current, duringthe spacing interval, is of likemagnitudebutflvreversed in direction. When transmitting fromlthedifferential sending end, the line current for the spacing interval isin the same direction asthat for the marking interval but the linecurrent is increased. In this particular. embodimentit'is increased toapproximately 46 milliamperes.

FEATURES F THE INVENTION One of the important features of the inventionherein is the line switching arrangement, The line switching isperformed by a line switch. The line switch is connected between therepeater and the line. It is arranged so that it may be actuated tothree different positions depending upon the type of service which therepeater is to provide, as follows:

1. When the line switch is in position l., the repeater herein isarranged to function as the polar sending end of a type B polarentialrepeater;

2. When the line switch is in position 2, the repeater herein isarranged to function as the polar receiving end of a type B polarentialrepeater;

3. When the line switch is in position 3, the repeater herein isarranged to function as a twopath polar repeater.

Another important feature of the invention herein is the local switchingarrangement. The local'switching is performed by a local switch. Thelocal switch is provided for conditioning the local side of the repeaterfor connection to the circuits with which the repeater herein isrequired to operate. The local switch may be actuated to ve diierentpositions to provide five different connections for the local side ofthe repeater, as follows:

l. When the local switch is in position l, the local side of therepeater herein is arranged for termination in a printer;

2. When the local switch is in position 2, the local side of therepeater herein is arranged for termination in any one of three diierentfacilities as follows: 1, a line circuit of a switchboard; 2, a lineunit comprising a line relay which is a receiving relay and the sendingcontacts of a printer; 3, a printer station;

3. When the local switch is in position 3, the repeater herein isarranged for termination in the local side of a carrier terminal;

4. When the local switch is in position 4, the repeater herein isarranged for service as the first half of an intermediate repeater. Asecond repeater such as the repeater herein is required to -function asthe second half of the intermediate repeater;

5. When the local switch is in position 5, the repeater herein isarranged for service as the second half of an intermediate repeater. Therepeater herein may then cooperate with a second repeater, such as therepeater herein, having its local switch actuated to its position 4.

When the local switch is in position 5, the repeater herein, instead ofbeing connected to another repeater such as the repeater herein, may

`be connected instead to an electronic regenerative repeater disclosedin the copending application, Serial No. 556,352, R. B. Hearn, J. A.Krecek, filed September 29, 1944.

A third important feature of the invention herein is an oscillatorcircuit which provides 1000- cycle tone for use when the system isoperated by manual Morse operation. The oscillator consists of a neonlamp, a condenser, a variable resistance and a fixed resistance. A jackis provided for patching a receiver to the oscillator circuit. When thereceiver is not connected to the jack, contacts on the jack disconnectthe oscillator circuit. A telegraph key is provided for manual sending.

Another important feature of the invention herein is the combination ofa special power supply circuit with the repeater equipment. In thepresent embodiment a rectifier in the power supply circuit rectifies or230 volts, 50 to 60- cycle power, to direct current power. Anautotransformer is included in the power supply circuit to reduce thevoltage to 115 volts for the operation of the printer when the primarysource is 230 volts. A 115-volt-230-volt switch is included in the powerunit to switch the internal connection for 115 volts or 230 volts asrequired. A gang switch is provided external to the power unit formaking the proper connection when the power source is 115 volts directcurrent or 115 volts or 230 volts alternating current. Two fuses, one inthe power unit and one external to the power unit, protect the primaryside `of the power unit. Two other fuses external to the power unitprotect the secondary side of the power unit. Two switches are providedfor adjusting the output voltage from the power unit. One of thesevoltage adjustment switches is for changing the voltage in coarse stepsand the other for ine steps. The repeater is equipped with a socket tofacilitate connection of the power supply to the printer.

A further feature of the invention herein is a special arrangement ofswitching for adjusting the line current and capacity.

A switch for adjusting the line current in coarse steps is provided formaintaining an approximate adjustment of the line current. This switchalso performs the function of connecting capacity across line currentregulating resistances, thus providing low terminating impedance for therepeater. A continuously variable resistance for adjusting the linecurrent is provided to obtain an accurate adjustment of line current.The adjustment which can be obtained with the variable resistance islimited, so that the switch for adjusting the line current in coarsesteps must be used to obtain the full range of permissible'adjustment.

A further feature of the invention is an improved anti-kick oifarrangement for preventing the receiving relay from kicking off when therepeater herein transmits into a line of high capacity. A number ofanti-kick off arrangementsare known in the art but none of the presentlyknown arrangements is suitable for application in the present repeater.This is attributable in part to the fact that the capacities of thelines on which the present repeater is designed to function are greaterthan the capacities of lines for which the presently known anti-kick offarrangements are intended to function. The anti-kick off featurecomprises a two-unit varistor and a condenser, and the speciallyarranged manner of connection of these units to the receiving relay soas to prevent kick-oif of the relay due to the inordinately heavycurrent surges from the lines on which the repeater will functionespecially in military service.

The foregoing and other features will become apparent from the followingdescription when read with reference to the drawings herein showing apreferred embodiment of the invention, in which:

Fig. 1 is the left-hand portion and Fig. 2 the right-hand portion of acircuit schematic showing the combined repeater of the invention, whichcombined repeater can be controlled through the operation of the lineswitch to provide three different optional arrangements of the internalconnections of the line side of the repeater to operate in threedifferent manners and through the.

operation of the local switch to provide ve difoperation.fpolarential-operation;

ferent optional arrangements of Jinternah concnections 4-ofthe-.locallside of the repeater to "oper- `ate-with eig-htvfdierentlexternal "facilities, all.v of "which optional arrangements areseparately "shown on other "drawing-l iigures'f herein for con-'venience;

Fig. 3 is a simplified circuit schem'aticfshowing the @ine-'sident Atherepeater per'Figs.` lf-and 2 voperating polarential; polar sending;

'Fig. -4 is -a`- sixnilied schematic showing the "lineside of' theVrepeater per; Figs. 1I an'dv2 `operating type B polarentiaL'differential sending;

lFighV-is a-simplii-'led-schematic showing the "line "side'of therepeaterfperfFigsQ-l and`-12 operating two=path polar; I y

`=Fig-.6 is'afsinrplied k-schematlc showing the v'repeaterandpowercircuit-with theline side of t'he-repeaterfperlFigs. 1 andZtarranged vfor polarentia1,- polar sending and the ilocal` side con--nected to a lprinter;

Fig. -"7-` isl a simplied schematic showing the rlocal side oftherepeaterper- Figs. 1 andf2 operatlocal Side of the-repeater per Figs.y1l and 2 operaty ing Iwith a'- switchboard;

Fig. 9isa simplied schematicfshow-ing the localsidef therepeater-per-Figs; land 2 operating with aline unit;

Fig. l'isasimplied schematic showing the r; llocalside' of the repeaterper Figs; 1 and 2 operatn ing-withfamrinter station; v

-Figfl is a-sim-plied schematicshowmg'the "local side of the repeaterper Figs. land 2operating with a `carrier telegraph terminal;

y"Fig.'12 Eisasimplified schematic-showing the local `side of? tworepeaters per Figs.- 1 and 2 arranged'k tolifunctionas anintermediaterepeater Fignl is -a'-si1nplied schematic showing' the rep'eaterper-Figs l and 2 .cooperating withI an electronicregenerative repeater,lthe' :two ccrn- Abined to serve asan intermediate repeater;

Figflli: isa simplid schematic ci the manual `telegraph set which ispartofthe repeaterper "Fia 1:

' Fig." 15 Yis a simplied schematic showingv both endsv ofacircuitarranged for type B polarential l It"is-`used in explainingfthetype B Fig. 15Af isI an explanatory diagram showing the signalburrentreceived at the diierential lend from signals transmitted from the polary transmit-tingend of a type B polarential circuit;

" Fig. 15B is an explanatory diagram showing 'the signal currentreceived at thepolarend from signals transmittedffrom the differentialsending end of a type'vBpolarentialcircuit;

yiFigd is afsimplifier schematic showing the :two channels ofa circuitarranged for two-path pelar operation;

Fig.' 16A is an explanatory diagram showing the signal current receivedat'r one terminal of a' twopath polar circuit; and

of Fig. 1 connect to conductors in' corresponding fwith'a local-printer-connected'at Vthe'intermediate` point;

positionsy extending toithe Ylefthand'i margin I of ='Atf theL :upperleft of 1 the 1 drawing, Fig. .2 1,2-"two lines.' i andf2,areshown'connected'.toi two` terminals-i3 andli, respectively. Line*` ifis usedfor condition f JforI polar sending `-lor polarL receivingvpolarential.` operation. Line' l is used-.alsof asf 'the -sending 'lineintwo-path polar operation. f-Line 2 is fused o-nly intwo-patli"polarioperation and `serves `as thereceiving line fin lsuch operation.

lower right of-Fig. '2,'are1nsed in e`stab1isliing connections on thelocal sidelof the repeater.

` The Various linearid Llocal yoptions are obtained by manuallyadjusting line switch l I land? local switch i5. The vmanuallyioperable'-l-inefy switchY i i compriseswfour separate unit switches -l2,"l3,f i4

and l5. 'The manually operable-ilocal switchfflii comprises fourseparate `unit swit'chesljf |1213 and la. Switches Il fandii-Eiare-rshownfin-their `lrst positions-*which are extreme clockwisepositions for each switch. Wheneither thef=line switch Il or the localswitchA l5i-is actuatedpall of the unit` switches assocatedrwithf they'particular 'switch are operated in- -unison asfy each unit Vswitch isrigidly attachedtov thesame' single rotatable shaft on theparticularswitch. lThatfis ttosayf-when switch l I is operatedjfforinstance, `by-imrning its rotatable shaitllina counter-clockwisedirection, as indicated-by'thev arrows, each .of units l2,` i3, lli and`I5 is"--actuatedcountern clockwisein unison. Arranged aboutA thezpar--ticular switch units lat pointsl iny the circumferenceof circlesconcentric ywit-inthe 'rotatable shaft are twelvestuds,extendingradiallylfrom each of which is a contact. I Certain-ofthesecontacts will engage certain arcuate segments of the switch iii-each ofthe segments possible positions. i Cer f ta in other contacts will, thearcuate se.,-

mentsonly in la particular-position. *Reference to switchunit l2 willillustrate the general 'manner of operation for all switch units.I1-Switchunit 'Ii 2 has three arcuate segments 2t, 2 if and 22. Each ofthe arcuate segmentsffhasea projection'v such ast?. -In the position`shown, which is theffrst position for the switch, aconta'ctconnected'to stud i--or the twelve switch studs associatedywithfunit switch i2, engages projection''i and acircuitis established'through segmenti 2d? to thev contact associated with stud 5. vIn theldescriptioncto follow the contact associated 4with `each *ofthe'twelyef'studs associated with a particular switch unit willbe'designated by the lnuriibervoi the stud. 'For the first positionof-switch uniti l2, its contactfvwill engage -projectioniS-and a circuitis established from Contact ii through segment '2i to contact 8.Similarlyanother circuit is estab lished from contact 9 throughprojectionsl39 and segment' 22 to contactt i2. "Threecorrespondingcircuits lare established simultaneously through :ther correspondingcircuits y"ofi each Aof switch zunits.' 135m and E5. "When switchH-'isl'rotated counter-clockwise to the-second-oi its three'-po`si tionseach-one of' the' nineJ projectionson' the nine arcuate segrnentsof` thethree swit'chr units willdisengage from the contact withwhi'chit yis fshownl in" engagementen the draw'ingA andfu will engage `with the nexthigher .numbered contact inreach' insJa-nce. Thus projectionstifi-iandwill disengagei from contacts La 5 @ar-1drV 9 respectively, and willengage contacts 2, 6 and iii respectively. Contacts fi, 8 and l2respectively,

.howeverI will remain in engagement"wi-th"seg- `:.mentsfZlLfZl and 22respectively. Underfthis condition contacts 2, 6 and Ill will beconnected through segments 20, 2| and 22 respectively, to contacts 4, 8and I2 respectively. No connections are made to certain switch unitstuds, as to studs 2, 3 and 4 forfinstance, of switch unit I5. When theswitch units engage such studs, it should be obvious that no circuit isestablished through the corresponding segment for that particularposition. It may be mentioned in passing that each of switch units I6 toI9 of local switch I5 has but two arcuate segments. The operation of theswitch, however, should be apparent from the foregoing. Attention iscalled particularly to segment 42 of switch unit I9. From the wiring ofthe studs associated with switch unit i9, it should be apparent that nocircuit is established through segment 42 until switch unit I9 of localswitch I5 has been rotated counter-clockwise into its fifth or iinalposition, at which time projection 59 will engage its contact II toprovide a circuit through segment 42 to contact I2.

Before proceeding with the detailed description of the circuit theoperation of the line current coarse adjustment switch 60 will be eX-plained. Line current coarse adjustment switch 60 has only one switchunit. The one switch unit has two arcuate segments 6I and E2. Segment 6|has a projection |53. Segment G2 has a projection B4 which subtends alarger angle than the normal projection such as projection 63. Theswitch unit is shown in its first position which is the extremeclockwise position. The switch unit is manually operable and isrotatable counter-clockwise from its position as shown on the drawing tosucceeding positions. Attention is called to the fact that when switch60 is in its rst position, as shown on the drawing, no circuit isestablished through either segment. Attention is also called to the factthat contacts I and 6 are both long contacts and remain in engagementwith segments @I and 62 respectively, when switch IIl is rotatedcounter-clockwise into all of the succeeding switch positions.

When switch 60 is actuated counter-clockwise to position 2, a circuitwill be established from contact 1 through projection 63 and segment 5|to contact 6. Since no conductor is connected to stud 2 no operatingcircuit will be established from contact I through segment |52 fromcontact 2. When switch 60 is actuated to position 3 a circuit isestablished from contact 8 through projection G3, segment 6| and contact6. Another circuit is established from contact I through segment 64 tocontact 3. When switch 6d is actuated clockwise to its fourth position acircuit is extended from contact 9 through projection 3 and segment 6|to contact 6. At the same time the circuit heretofore traced fromcontact I to contact 3 will be maintained, while switch 6B is in itsfourth position. Coarse line current adjustment switch 6, as its nameimplies, is used in adjusting the line current'in coarse steps when thecircuit is being adjusted for service on the various line options.Switch 6G is supplemental by ne line current adjustment switch i8 whichmay be, as indicated in Fig. ;1, an ordinary resistance divisible intosections 'l5 and l@ by means of a sliding arm ll. Switch i8 is alsomanually adjustable. The manner in which switches II, I5, E0 and'l'function in the circuit will become clear from the descriptionhereinafter.

Power supply It is pointed out that the circuit described herein mayfunction with a wide variety of power services. It is contemplated thatunder certain circumstances power will be supplied in the eld from -agas engine driven generator. The power circuit is arranged so that itmay be connected directly to a 115-volt or 23Il-volt alternating currentsupply, or to a 115-voltdirect current supply, as a regular procedure.

The power circuit is shown in the lower lefthand corner of Fig. 1.Voltage from the power service is impressed across conductors 2|2 andEIS through lter 266 comprising series inductance and shunt capacitance.The condensers 209 and 2| are connected across conductors 2 I2 and ZIE.The inner plates of the condensers are connected together and to ground269. Inductance 257 is connected in series with conductor 2|2 and acorresponding inductance ZEJS is connected in series with conducto-r2|3. One side of the power supply circuit may be traced from conductor2|2 through inductance 2137, contact |59 of switch |54 and conductor |69which connects to the bottom terminal oi the autotransiormer |65. Theopposite side of the power supply circuit extends from conductor 2 i3,through inductance 202i, contact l of switch IES to conductor Il whichconnects to the right-hand or iixed terminal of switch |58. Theleft-hand terminal of switch |68 is shown connected to stud |67 whichconnects to the lower of the two alternate input terminals ofautotransformer |65. Switch |68 is set in this position when power issupplied from a 115volt alternating current supply. When 230-Voltalternating current is impressed across conductors 2 i2 and 2id, switch|58 is operated to engage terminal |65 which connects to the upper ofthe two alternate input terminals on autotransformer it. Variousterminals on the output side of autotransformer |65 are connected bymeans of taps to various studs arranged in a semicircle on switch I'Hwhich studs are arranged to be engaged by rotatable switch arm |72. Fromthe center point of switch |72 the circuit extends through fuse |13,upper terminal of the primary winding Vit of transformer Il!! throughthe primary winding Il@ to the bottoni terminal of autotransforiner |55.The secondary |75 of transformer I'M has Various terminals connected bymeans of taps to Various studs arranged in a semiycircle on switch |82.The studs are engaged by rotatable arm |33 which connects to thelefthand terminal of the full wave rectifier ITI. The rectifying unitsin the rectiiier may, for instance, be copper oxide or other units.Rectier Ill is composed of four arms each having individual rectierunits I i8, |19, and |85. The lower terminal of the secondary H5connects to the right-hand terminal of rectifier Il'i; The top terminalof rectier ITI is connected through inductance i355, conductor|88,contact ItI of switch |54 through fuse |52 to conductor |50. Thebottom terminal of rectifier ITI is connected through conductor |89,contact ld of switch IW and fuse |53 to conductor itil. condensers |35and |86 are bridged across conductors |88 and |89 to provide a lteringaction which reduces the ripple. Resistance |81 serves as an artificialload and assists in voltage regulation. The polarity of the circuit isfixed so that negative battery is supplied to the various apparatusunits in the repeater circuit from conductor |58 and positive battery issupplied from conductor I5I. Switches Il! and |82 provide means forregulating the voltage impressed on the output of the power circuit.Switch I'II adjusts in ne steps and switch |82 in coarse steps.

When the power service is supplied from a l15-volt alternating currentsource, power is supplied tc the motor which drives the printer over acir-cuit one side of which may be traced from conductor 212 throughinductance 2111, conductor 1911 and through inductance 193 of lter 152to one terminal of the motor. The opposite side of this path may betraced from conductor 213 through inductance 2113, contact 151 of switch154, switch arm 158, stud 161, contact 155 of switch 154, conductor 191and inductance 154 of lter 192 to the printer motor. When the powerservice is supplied from a 23o-volt alternating current source andswitch arm of switch 158 engages stud 155, the path extends through theupper of the two input terminals of autotransformer 1155 through thelower turns of the transformer to t-he lower of the two input terminalsof autotrans-former 165 to stud 161. From this point the circuit followsa path heretofore traced.

When the power service is direct current, switch 15d is operated to itsalternate position. For this condition the llvolt direct current supnply is connected directly to conductors 151i and 151 in the followingmanner: From conductor 21E through inductance 251 through contacts 161iand 152 of switch 155 in series and fuse 152 to conductor 1511. Theother side of this circuit may be traced from conductor 213 throughinductance 208, contacts 158 and 154 of switch 151i in series andthrough fuse 153 to conductor 151. Under this condition 1l5-volt directcurrent is supplied to the printer motor over a circuit which extendsfrom conductor 212 through inductance 2611, conductor 1911i andinductance 193 to one side of the motor. The opposite side of the motoris supplied from conductor 213 through inductance 253, contact 151i ofswitch 154, conductor 191 and inductance 194.

Fig. 6 shows the manner in which power from an alternating currentsource is furnished to a teletypewriter motor as well as to a repeaterarranged in accordance with one of the options herein. The power circuitconnections may be understood from the foregoing description. Theinternal connections from the power supply to the repeater and of therepeater will be described in detail below for each particular option.

General It is particularly pointed out that, because of the complexityintroduced into the circuit of the repeater herein, due to the provisionof the numerous options, first the paths constituting the branches ofthe circuits for each of the various options in Figs. l and 2 will betraced under separate headings and thereafter the operation of thecircuit for each of the options will be described with reference toindividual simplified gures corresponding to each option under anotherindividual heading for each option.

CIRCUIT FOR LINE SIDE or REPEATER OPERATING POLARENTIAL, POLAR SENDINGThe rst line option which will Abe described is that for the line sideof the repeater operating polarential, polar sending. In order toarrange the circuit per Figs. 1 and 2 to function for this condition, itis necessary to establish a circuit in Figs. 1 and 2 which correspondsto the arrangement shown in Fig. 3. How this is performed will now beexplained,

For this condition line 1, which connects to terminal 3 in the upperleft-hand corner of the drawing, is used and line 2, which connects to10 terminal 4, is not used. Line 1 connects to a distant polarentialrepeater arranged for polar receiving. Such repeaters are Well known inthe art and are described in the patent to Cramer mentioned above. Forthis option switches 11 and 15 are both in position 1 which is theposition in which both are shown in the drawing. It was mentioned abovethat line 2 is not used on this option. Line 2 is, therefore, open forthis condition. This may be seen by tracing the circuit which extendsfrom terminal 4 through line 2, inductance BS of filter 65 and conductor108 which connects to terminal 1 1 of unit 12 of switch 11. Terminal 11is open as projection 39 is in the condition indicated in the drawing.

As the Various branches of the circuits are traced it may be desirableto refer to the corresponding branch in the electrically equivalentligure. In this case comparison would be made with correspondingbranches in Fig. 3. It is pointed out that the paths may not passthrough windings on the relays located in the same physical position ineach instance and there may not be exact correspondence in other minorparticulars, but the circuits functionally are exactly the same. Theindividual separated figures will Ibe used in explaining the operationfor the various options hereinafter.

The circuit from line 1 is closed. This circuit may be traced fromterminal 3 through line 1, inductance 61, inductance 11, conductor 1112,variable resistance 19, resistance 85, conductor 110, variableresistance 16, switch arm 11, conductor 105, contact 9 of unit 12,projection 311, segment 22, contact 12, conductor 222, winding 92a ofthe receiving polar relay 92, conductor 220, contact 4 of unit 12,segment 2li, projection 31, contact 1, conductor 199, conductor 200,conductor 221 which extends into Fig. 2, and con- .ductor 331 whichconnects to the armature of sending polar relay 216. A nrst branchextends from line 1, through the protector blocks to ground. A secondbranch extends from line 1 through filter condenser 159 to ground 10.third branch extends through resistance 12 and condenser 13 to terminalI of switch 60' and to the top terminal of variable resistance 18 invparallel by way of conductor 104. A fourth branch extends throughcondenser 14 which may be cut into the circuit when switch B0 is invarious positions. Variable resistance 19 positions of switch 60 whichshould be understood from the foregoing. When switch 60 is in its fourthposition all three resistance units 19A, 19B and 19C areshort-circuited. Milliammeter 214 is connected across resistance over acircuit which may be traced from the top terminal of resistance 85,conductor 112, resistance 83, contact 88 of key 86, milliammeter 214,contact 89 of key 85 and conductor 113 to the bottom terminal ofresistance 85.

rectifier 96, rectifier 95, winding 92e of relay 92, conductor 128,contact 8 of switch unit 15, segment 31), projection 50, contact 5,conductor 122,

resistance 120, conductor 121, conductor 136 and" is' divisible intothree units which may be connected into the circuit in Various mannersfor various Another branch circuit extends from conductor 2110,`

analoger,

through, the.y biasing4 winding 92h of relay 92 which extends fromnegative batteryv supplied throughconductor I50, conductor 2I6,conductorA I 33, contact 8 of unit I3, segment 24, projection 44,contact 5, resistance I34, conductor |23, resistance |25, conductor 225,winding B2b otrelay92, conductor I30, contact 4. of switch unit. I4,segment 26, projection 46, contact I, conductor I23, conductor II5 andconductor I5I which connects to positive battery. There is anotherbranch circuit which may be traced from conductor |95 at the top rightof Fig. 1, through conductor 223, contact of unit I2, segment 2I,projection 38, contact 5, conductor I I6 and resistance IIS to theleft-hand-terminal ofresistance |20. Still another branch path maybelgtraced from terminal of unit I2 through resistance .I02, terminal 3ofunit I3, projection 45, segment 25, contact I2, conductor 202, whichextends into Fig. 2, to conductors 335 and 3.33 in parallel. Contact 335connects to open spacing contact 211 of relay 216 and conductor 333,connectsto closed markingcontact 214 of relay 2.15,` The. armatureofrelay4 215 is connected ayer av path through conductor I 44, whichextends into Fig. 1, contact I2 of unit I5, segment 31|, projection5|and contact 9 to ground. Positivev battery is `connected to contact 214of relay 215.and to contact 211 of relay 216. The circuit maybe tracedfrom positive battery in Fig. 1 through conductor I5Iwhich extends intoFig. 2,'conductor 256, resistance 365 and conductors 33,3,and 335.inparallel to contacts 214and 211.

Negative battery is connectedto contact 213 of.

re1ay215 and to contact 218 of relay 216., The circuit extends fromconductor |50V in Fig. 1, through conductor 2I1 which extends into Fig.2, conductor 251 and conductor 314, to terminal 2,13, of relay215gand tocontact 218 of relay 216. Contactr213 of relay 215 and contact 215 ofrelay 216.are connected to contact 211 of relay 216v and to vContact 214of relay 215respectively, over apathr which may be traced from contact213 and contact 218, through conductor 315A through resistance 212,conductor 204 which extends into Fig. l, contact 9 of unit I3,projection 45, segment 25, contact I2 and conductor 202, which extendsinto Fig. 2, where it. connects to contacts 214 fand 211 throughconductors 335 and 333.-

It Iis particularly pointed out that in a number 0tthelocal optionarrangements yto -be described hereinafter the line side` of therepeater will be assumed to be in the condition tracedunderths headingandthe battery connections to the con-v tactsyofrelays 215 and 216 willybe the same `as traced herein. This is the condition which obtains whenthe line switch is in position I for polarential operation ywith polarsending. The manner in which the circuit functions whenv arranged inthis condition and for each of the other optional conditions will beexplained hereinafter after the circuits are rst traced for all options.

It once more particularly pointed out that in order for the reader tounderstand thearrangement of the circuit per-Figs. 1 and 2 obtained as aresult of each one ol the optional adjustments, it will probably benecessary to refer to thecorresponding individual circuit per Figs.3.,to 14 herein.

CIRCUIT FOR LINE SIDE 0F REPEATER OPERATING POLAYRENIIAI., DIFFERENTIALSENDING Thecircuit for the line side of the repeater operatingpolarential, differential sending, will now begtraced. Comparison maybemade with-the.

circuit per Fig. 4 which is-vfunctionally identical.

For this condition line I is used and line,-2. ist not used. The lineswitch II is operatedtol itsI second position. In this position, as maybe understood from the foregoing, each ofv the projec tions on each ofthe three segments of eachoffthe four switch units is disengaged fromthe Contact with which it is in engagement, as shown on the drawing, andit is rotated clockwise to cngage'the next higher numbered'contact ineachinstance.v Local switch I5 will be assumed to remain in its firstposition as shown on the drawing.

Refer now to Figs` 1 and 2. A circuit may be` traced from terminal 3through line I, ind'uctance 81, inductance 1I, conductor III2, conductorIll-.1,

terminal I5 of unit I2 of switch I I, projection 33,

segment contact I2, conductor relay. winding 02a, conductor 225,terminal oi' switch unit I2, segment 20, projection I, Contact?,conductor III9, conductor 255, conductor 221, which extends into Fig. 2,and conductor @BI which connects to the armature of relay 'romthiscircuit just traced, branches extend through the protector blocks andthrough condenser. 55' to, ground in each instance. A circuit maybetraced' from conductor 200 through rectiers 35 and 35;' in series, relaywinding 52e, conductor I23,1con tact 8 of switch unit I5, vsegment 33,projection 56, contact I5 and conductor I2'I which reconnectsalso toconductor 205. From conductor'IQQla. circuit may also be traced throughconductor y142253, contact 6 of switch unit I2, segment 2 I, projection38, Contact 5, conductor 224, conductor 225, relay winding 52h,conductor ISI), contact 6I of switchunit I4, segment 25, projection 45;contact Zand-f conductor |43 which connects to the junction-be.- tweenthe top terminal of rectifier 35 and the right-hand terminal of relaywinding- 62e. A branch may also be traced from the junction betweenrectiflers and 35l through condenser 91, conductor I42, conductor U36,resistance E41,- contact I0 of unit I5, projection 5I, segmentii;contact I2 and conductor M4, which extends into Fig. 2 and connects tothe armature of relay 215 Positive battery is connected to terminal2140i: relay 215 and terminal 211 of relay 215; The circuit may betraced through conductors 333 and 335 in parallel to conductor 252 whichex tends into Fig. 1, through contact I2 of unit I3, segment 25,projection 45, contact III, conductor II5 and conductor I5I to positivebattery. Contact 213 of relay 215 and contact 21S of relay-216i. areconnected in parallel and through conductors- 315, 251 and 2I1, whichextends into Fig. l, to.. conductor I55 which connects tol negativebat-,- tery. ,For this condition, however, groundv is connected to thisside of the power supply circuit over a path which may be traced fromconductor-- |55 through conductor Zitl in Fig. 1, conductor: I33,Contact 3 of unit I3, segment 24, projection.. 44 and contact 6 andground.

CIRCUIT FOR LINE SIDE or' REPEATER OPERATING Two-PATH POLAR The circuitfor the line kside of. the repeater.. operating two-path polar will nowbe tracedf, Comparison may be made with the circuit, per. Fig. 5 whichis functionally the same.

For this condition, lines I and'2 areibothused;` The line switch I I isoperated to its thi-rd position', Local switch I5-remainslin its rstpositionf as; shown on the drawing. A circuit Imay -be traced" fromterminal 3-through line I, inductance`61, inductance 1I, conductor`I02J, conductor |013; variableresistances 19a, 19b and 19e, resistancee85, conductor ||0, variable resistance 18, sliding arm 11, conductor|05, contact 1 of unit |2, projection 38, segment 2|, contact 8,conductor 223, conductor 200, conductor 221, which extends into Fig. 2,and conductor 33| which connects to the armature of relay 216. Branchesextend from this path through the protector blocks and condenser 60 toground as heretofore traced. Branches also extend through resistance 12and condenser 13 in series and through condenser 14, shuntingresistances 13, 85 and 13 as indicated in Fig. 5. Milliammeter 2|4 isconnected across resistance 85. These paths have heretofore been traced.A circuit may also be traced from terminal 4 through line 2, inductance50, conductor |08, Contact of unit |2, projection 39, segment 22,contact |2, conductor 222, relay winding 92a, conductor 220, contact 4of unit |2, segment 20, projection 31 and contact 3 to ground 9|. Abranch may also be traced from conductor 200 through rectiiers 96 and 35in series, relay .winding 32e, conductor |23, contact 8 of unit i5,segment 30, projection 50, contact 1, conductor |39, conductor |32,resistance |34, contact 1 oi unit I3, projection 44, segment 24, contact0, conductor |33 and conductor Zit to conductor |50 which connects tonegative battery. Another branch of the circuit may be traced from thejunction between conductors |33 and 213 through conductor |2|,resistances |20 and I3, conductor IIB, resistance |02, contact of uniti3, projection 45, segment 25, contact I2 and conductor 202, whichextend into Fig. 2, to conductors 333 and 335 in parallel which connectto contact 214 of relay 215, and contact 211 of relay 215, re-

spectively. Contact 214 of relay 215 and con-v tact 211 of relay 213connect through conductors 333 and 335 in parallel through resistance365 and conductor 256 to conductor |5| which connects to positivebattery. Contact 213 of relay 215 and contact 218 of relay 215 areinterconnected by conductor 313 which connects through 315 to conductor314 and through conductors 251 and 211 to conductor |50 which connectsto negative battery. A circuit may also be traced from contact 218 ofrelay 215 and contact 213 of relay 215 which are interconnected throughconductors 313, 315 through resistance 212, conductor 204, which extendsinto Fig. 1, contact of switch unit |3, projection 45, segment 25,'contact |2, conductor 202, which extends into Fig. 2, to conductors 333and 335 in parallel which connect to contact 214 of relay 215 andcontact 211 of relay 215, respectively.

CIRCUIT FOR LOCAL SIDE oF REPEATER OPERATING WITH PRINTER The circuitfor the local side of the repeater operating With a printer will now betraced. Comparison may be made with the circuit per Fig. 7 which isfunctionally the same. The line side of the repeater may be arranged inany of a number of conditions. It Will be assumed,

however, that the line side is arranged for polarential, polar sending.For this condition, the line switch il will be in position To arrangethe local side of the repeater for connection to the local printer, thelocal switch |5 will also be in position 1. Both switches and I5 will,therefore, be in the conditions shown on the drawing.

Line only is used for this condition, as heretofore explained, and thecircuit for the line side of the repeater, including the batteryconnections to the contacts of relays 215 and 216 are the same asheretofore traced for the polarential polar sending condition and willnot, therefore, be retraced.

On the local side of the repeater no external connections to contacts 8,5 and I0 are required. The plugs of the receiving printer magnet and ofthe printer transmitter are inserted in their respective jacks. Contact232 is opened.

A circuit may be traced from positive battery through conductor |5I,conductor 243, conductor 243, conductor 255, conductor 25|, projection51, segment 20, contact |2, conductor 259, resistance 332, which isshunted by condenser 343, inductance 331, sleeve 302 of the receivingmagnet jack, sleeve of the receiving magnet plug, winding of thereceiving magnet, tip of the receiving magnet plug, tip 303 of thereceiving magnet jack, conductor 344, conductor 345, sleeve 290 of theprinter transmitter jack, sleeve of the printer transmitter plug,printer transmitting contacts, tip of printer transmitting plug, tip 23|of printer transmitter jack, inductance 294, conductor 330, conductor321, conductor 328, projection 53 of unit i5; segment 33, contact |2,conductor 20|, which extends into Fig. 1, marking Contact 94 andarmature of receiving relay 92, conductor [53, conductor 226 whichextends into Fig. 2, contact 5 of unit i5, segment 32, projection 52,contact conductor 353, conductor 354, conductor 251, conductor 211 whichextends into Fig. l, and conductor |50 which connects t0 negativebattery. From the sleeve of jack 200 a circuit also extends throughinductance 295, conductor 350, conductor 334, conductor 350, contact ofunit l1, projection 54, segment 34, contact t, conductor 352, relaywinding 216a, conductor 356, relay winding 215er, conductor 322, contact5 of unit i9, segment 4|, projection 53, contact and resistance 245which joins conductor 238 from which point the circuit has been tracedto 'positive battery. A circuit may also he traced from positive batterythrough conductor |51 which extends into Fig. 2, conductor 255, relayWinding 2150, conductor 355, relay winding 215C, conductor 258, contact6 of unit i8, segment 35, projection 53, contact I, resistance 233,resistance 234, resistance 235, conductor 242, conductor 211, whichextends into Fig. 1, and conductor |50 to negative battery.

A circuit may also be traced from open space contact 53 of relay 92 inFig. l through resistance |25, conductor |3I, conductor 203, whichextends` into Fig. 2, contact 1 of unit l1, projection 55, segment 35,contact |2, conductor 35|, relay winding 213D, conductor 351, relaywinding 2155 and conductor 34| to conductor 255 which connects over apath heretofore traced to positive battery.

Crecurr son LOCAL Sins or REPEATER OPERATING WITH SWITCHBOARD Thecircuit for the local side of the repeater operating with a switchboardwill now be traced. Comparison may be made with the circuit per Fig. 8which is functionally the same. it will once more be assumed that theline side of the repeater is connected so as to operate polarential withpolar sending. For this condition, as described heretofore, line i isused and line 2 is not used. Line switch remains in position 1. Thelocal switch i5 is in position 2 but the local terminal 8 shown at thelower right of Fig. 2 is connected externally to terminal 804 of aswitchboard as indicated in Fig. 8. The connections from terminal 3 forline are the same as heretofore traced to the armature of relay 210. Thepositive and: negative battery connections to the contacts of relays 215and 216 are also the same as heretofore traced. Reference to Fig. 8shows that in the switchboard a connection is made to negative l15vo1tbattery from which point a circuit is traced through the winding .ofwest relay 32|, make contact oi east relay 8e2, sliding contact ofvariable resistance 8%, switchboard terminal @dfi and external conductorB95 which extends to local terminal t as shown in Fig. 2 throughinductance 3F28, conductor 25d and conductor 35S to the junction betweenresistancei and ddii. It is pointed out that local terminal ii and theswitchboard terminal 83d' may be separated by a distance not exceedingiive miles. The circuit which extends through resistance 329 continuesthroughcontact 8 of unit I5, projection 53, segment 33, Contact I2,conductor which extends into Fig. l, marking contact 95. of relay 52,conductor |98, conductor 225, which extends into Fig. 2, contact (i ofswitch unit IS, segment 32, projection 52 and contact 2 to ground. Thepath which extends through resistance Slii continues through contact 2of unit Il, projection 54, segment 34,'contact 6, conductor 352, relaywinding 216m, conductor 355, relay winding 2'i5c., conductor 32d,contact 6 of unit I9, segment di, projection58, contact 2 and conductorMI, which extends into Fig. 1 and connects to the junction betweencontact vSli of relay 92 and conductor 25|. A-circuit may also be tracedfrom the open contact 93 of relay 92 through resistance |25, conductorI3I, Iconductor IIB, contact I of unit i3, projection 53, segment 23,contact Ji', conductor II'I, which extends into Fig. 2, contact of unitI8, rprojection 51, segment lli), contact I2, conductor 259, conductorfii, relay winding iitb, conductor 351, relay winding H619, conductor851, Contact I2 of unit II, segment 35, projection 55, contact 8,conductor`2il5, which extends into Fig. 1, contact I2 of unit It,segment 25, projection 48, contact 9, conductor 2 iii and conductor 65dto negative battery.

For this option a biasing circuit is also established which extendsthrough biasing winding 215e and 2'IBc. This circuit is the same as wastraced through the same windings for the condition where the local sideof the repeater is connected toa printer under the last precedingheading. Comparison may be made between Fig. 7 andFig. 8 `which showthat the biasing circuits are the same.

CIRCUITS FoR LooAL SIDE or REPEATER OPERATING WITH LINE UNIT The circuitfor the local side of the repeater operating with a line yunit will nowbe traced. Comparison may be made with the circuit per Fig. 9 which isfunctionally the same. For this condition it will be assumed that theline side of the repeater is operating polarential, polar sending. Theline switch will, therefore, be in position l. The local switch is inposition 2. The condition within the repeater circuit per Fig. 1 andFig. 2 is, therefore, identical with that described under the lastpreceding heading wherein the local side oi the repeater was connectedto a switchboard. The internal connections of the repeater, therefore,remain unchanged and are the same as shown in Fig. 8. Local terminal 8,however, instead of being connected to a switchboard is connected asshown in Fig. 9 to a line unit. The circuit may be traced from negative115-volt battery through transmitting terminals Sill, winding ofreceiving relay 902, variable resistance 9633,

le terminal 984 on the line .unit and through external conductor 905 tolocal terminait shown in Fig. 2.

CIRCUIT FOR LOCAL SIDE or REPEATER OPERATING WITH PRINTER'ISTATIONEQUIPPEnV/'ITH A MNE RELAY The circuit for the local side of the4repeater operating with a printer equipped with a line relay will nowbe traced. See Fig. 10. For this condition, also, the internalconnections of the repeater per Fig. 1 and Fig. 2 are the same asdescribed under the last two preceding headings. Local terminal 8,however, is connected to a printer station for this condition. At theprinter station a power supply Iii i 2 is connected to a rectiiier IMI.From the .negative terminal ofthe rectiiera circuit extends throughconductor IDM, conductor MI5, conductor lill, sending printer contactsILtop windingfoi polar receiving relay mi2, variabie resistance |525,through terminal |825 of the printer stati on and external conductor orline |021 to local terminal 8 of Fig. 2. A second branch extends fromnegative battery through conductors IilIli and Iill, resistance |569,bottom winding of relay |002, resistance IGM, conductor Il and conductor|020 to the positive terminal of rectifier yIIiII which is connected toground Iiilll. A vcircuit may also be traced from thenegative terminalof the rectifier through conductor II, conductor. IOII, resistance IMS,armature of relay IIlZ, contact IEIZI, resistance I, resistance IBM,Winding of receiving magnet Ill, conductoriliiand conductor |626 to thepositive side of rectifier IGI I. From open contact |522 of relay |002 acircuit may be traced through resistances |856 andl |685 which connectsalso through conductor I|i|9 and conductor |92!! to the groundedpositive side of rectifier Iill I.

CIRCUIT FOR THE LOCAL SIDE or THE REPEATER OPERATING VIITH A CARRIERTELEGRAPH TERMINAL The circuit for the local side of the repeateroperating with a. carrier telegraph terminal will now be traced.Comparison may be made with the circuit per Fig. 11 which isfunctionally the same. It will again be assumed that the line side ofthe repeater is connected for polarential, polar sending operationinaccordance with Fig. 3 herein. The line switch will be in position 1.The local switch is operated to position 3. rLocal terminals 3 and 9 inthe lower 'right-hand portion of Fig. 2 are connected externally asshown in Fig. 11 by means of conductors or lines |||5 and I I I4 to thecarrier telegraph terminal.. The carrier telegraph terminal with whichthe repeater herein cooperates is well known in the art asthe CF2 orCFZB carrier telegraph terminal manufactured by the Western ElectriclCompany, Incorporated. It is described inthe Bell Laboratories Recordfor May 1944, volume XXILNumber pages 494 to 408, published rby the`Bell Telephone Laboratories, Incorporated. `The circuit to which therepeater herein connects vis shown on Fig. 3011 page 406 thereof. The.sending and receiving relays of that gure correspond to relays H01 andHB5 respectively. of Fig. 11 herein. The loop is modified as shown inFig. 11 herein.

Refer now to Fig. 11. A circuit may be traced from positive battery IIB!at the telegraph carrier terminal through contact I |03 and the armatureof the receiving relay HEI-5 through the top winding of break relay H06and the top winding of sending relay I |81 through variable resistanceH88, terminal III2 and external conductor or linezI I I5 to localterminal8-in Fig. 2. A-branch of this circuit extends from a junctionbetween the armature f the receiving relay and the top winding of relayII86 through the bottom Winding of relay II86, bottom Winding of relayl||81 and resistance I|89 to positive battery I |8I. Between the bottomWinding of relay H81 and resistance |I89, a variable resistance II|8 isconnected to ground. A circuit may also be traced from negative battery|I82 through variable resistance IIII, terminal III 3 and externalconductor or line II|4to local terminal 9 in Fig. 2. Reference is nowmade to Fig. 1 andFig. 2. From local terminal 8 a `circuit extends`through, inductance 388, conductor 2681, terminal 3 of unit I9,projection: 58, segment'4l, terminal 6, conductor 324, relay Winding215a, conductor, 356, relay Winding 216cv, terminal-.9 ot `unit I6,projection 53, segment 33, Contact I2, conductor 28|, which extends intoFig. `l., terminalz94vand armature of relay92, conductor-. I98fconductor 226, which extends into' fFig." 2, terminall cfu-nit I6,segment 32, promotion-52,' contact. 3,.: conductor 325, conductor` 26 I.and "inductance -3'I 3 to terminal 9 fromwhiclr point :the circuit wastraced to negative vbattery I |82 at the telegraphcarrier terminal. Avcircu-iftam-ay also betracedtrom the open contact '93fofrrelay-92through resistance |26, conductor 283, which-.extends'into 2j,contactsof' un-its- I1,= yprojection 55, segment 35", con tact I2,conductor 35|-, relay` winding-216b, conductor 351, relay'wirrding2155,'1 conductor 34|, conductor 259,1 contact I 2.0i? unit-J8,-seg-ment 48, projection. 51 and'. contact 9-toground; The connection toline I-` and. the :connections from-positivev and negati-ver battery:to.4 the contacts of Yrelays 215 and 216 are :as-.previouslydescribedf'or Iig.A 3 above.

CIRcUITA Fon LOCAL Sima` or` TWo RPE'ATERS PROVIDING4` INTERMEDIATE"OPERAI-rioni Wrrn A PRINTER The circuit forthelocal sid'eof. tworepeaters per the invention herein ,interconnected l .to provideAoperation atl an intermediatepoint on ,aline and having a. printerconnected at the vintermediate `point will now. betraced. Comparison'may be made with thecircuit perFig, 12; which is functionally the sameItwillagain be' assumed that the line side of. eachof. the tvvorepeaters is. connected .for polarentialoperation with polar sendingas.in Fig.. Sher-ein.. Inl order to arrange the circuits` for this'.optiongfitlils' .necessary to have two repeaters-sueltas thatof`.c0mbine`dFig'. 1 'and Fig.y 2 herein,` having their. local sidesinterconnected as shown. in Fig. ,12. The local switch of the repeatertoawhicnthe' printer is` connected must' be operated to position` 4 andthe local switch of thesecondrepe'ater-to which yit irsinterconnectedmust be operateditoposition 5". The local binding posts 8, 91 andilfll''or one repeater areA interconnected byV means ofi three externalconductors to the local binding posts 8`i- 9and`-v |18 respectively,of.y the: cooperating repeater.. The circuit corresponding to?t ther`rightehandzf repeater shown in Fig. 12 Willrfrstbetracedi im Figs; 1andZ. Attention is'fparticularly called-ftothefact that thev localiswitchr ferA this fconditionfis imposition 5. A circuitl may `beatracedfrom, terminal 8; through. inductance 388,-1 conductor, 268, conductor,348,v resistances, 346'; and', 34Tlvin series', terminal 5 of: unitI.T,1projection.54', 'segment 34,

te'rn'n'nal 6`, conductor" 352i; relay Winding 21621,.

conductor 356, relay Winding 215a, conductor 324, terminal of unit I9,seg'ientAI, projection58, contact 5, conductorV 248,coducto'r 258,conductor252, conductor 25.3,- co'r'itact II of unit |9, projection 59',segment 42, contact I2, conductor 255 and inductance 3|4 to localterminal I8. A circuit may also be traced from local terminal 9 throughinductance 3I3, conductor 26|, conductor 326,` contact |I of unit I6,projection 53, segment 33',k contact I2, and conductor 28|, whichextends into Fig; 1, contact 94 and armature of relay 92, conductor |98,conductor 226, Which extends intoFig. 2, contact 6 of unit I6, segment32, projection 52', contact 5, conductors 353, 354, conductor 251,conductor 2`I1, which extends into Fig.1, and conductorv |58 to negativebattery. A. circuit may alsojbe traced from the open contact 95|-v ofrelay 92 through resistance |26, conductor I 3|', conductor 203,` whichextends into Fig. 2, contact II of unit I1, projection 55, segment' 35,contact I2, conductor. 35|, relay Winding 2161), conductor 351, relayWinding 21517, conductor 34|, conductor 259, contact I2 of unit i8,segment48, projection 51, contact II, conductor 253, contact I I of unitI9', projection 5 9, contact I2, conductor 255 and inductance 3I4 tolocal terminal I8. A branch oi the circuit last traced extends fromconductor 253 through conductors 252, 258, 248, 246 `and I 5I to'positive battery. A circuit may also beA traced from negative batteryin` Fig. 1 through conductor. |58, conductor 2|1, which extends intoFig. 2, resistances 235,234 and'236', contact '5" of unit I8, projection56, segment. 36;v contact 6, conductor' 258, relay4 winding 215e,conductor. 355, relay Winding 216e, conductor 256 and conductor I5|which `extends to positive battery in` Fig. 1. The connection to line Iandthe positive andV` negative battery connections" to' thev contacts ofrelays 215 and 216 are the same asr previously traced.

NOW the circuit for the left-hand repeater of Fig. 12 will be traced'.As explained in the foregoing', a secondrepeater such as Fig. 1 and Fig.2 is" required. Since the printer is to be connected to' the' left-handrepeater, the local switch of the repeater Will be operated to position4. The line Switch, as explained above', is maintained in position* 1'.

A circuit may be traced from local terminal 8 through inductance 388,conductor :268, conductor 348;. resistance 346, resistance 341, terminal4 of unit I9, projection 58, segment 4|', contact 6, conductor'324',relay Winding 215e, conductor 356, relay vvinding 216e', conductor 352,contact 6 of unit I1, segment-34, projection 54', contact 4, conductor358; conductor 334, conductor 348, inductance 295, sleeve 298 of theyprinter transmitter jack, sleeve of the printer transmitter plug,printer transmittingA contacts,- tip of printer transmitter plug, tip 29I `of printer transmitterjack, inductance 294, conductor 338, conductor321, contact I8 of unit I 6, projection 53', segment 33, contact I2,conductor 28|, which' extends'into Fig. 1, contact 94 and armature ofrelay 92, conductor |98', conducto'r' 226, Whichextends-into Fig. 2,contact 6 of 11n-it 65', segment 325, projection 52, contact 4,conductor 325, conductor 26|' and inductance 3|3 to local. terminal 9.A` circuit mayv also be traced from teri'ninaly I8 through inductance3|4, conductor 255; conductorv 254, contact I8 of unit I8, projectionl51, segment 49, contact- I2, conductor 259,-resistance342,whichis-shuntedby condenser 343, inductance 381, sleeve 382 of thereceiving Winding of receiviiigrn'ag'net, tip of receiving inag- 19 netplug, tip 303 of receiving magnet jack, conductor 344, and conductor 345which joins the path last traced at jack sleeve 290. A circuit may alsobe traced from the open contact 93 of relay 92 through resistance |26,conductor |3|, conductor 203, which extends into Fig. 2, contact of unit|1, projection 55, segment 35, contact |2, conductor 35|, relay Winding216b, conductor 351, relay winding 215b and conductor 34| which connectsto the left-hand terminals of resistance 342 and condenser 343. Fromthis point the circuit has been traced to local terminal l0. Anothercircuit may be traced from negative battery in Fig. 1 through conductors|50 and 2|1 which extend into Fig, 2 through resistances 235, 234 and236 to terminal 4 of unit |8, projection 56, segment 36, contact 6,conductor 258, relay winding 215e, conductor 355, relay winding 216e,conductor 256 and conductor |5| to positive battery.

CIRCUIT FOR LocAL OPERATION WITH ELECTRONIC REGENERATIVE REPEATEP.

The circuit for the local side of the repeater herein connected to anelectronic regenerative repeater Will now be traced. The electronicregenerative repeater with which the repeater herein cooperates for thisoption is disclosed in copending application, Serial No. 556,352, R. B.Hearn, J. A. Krecek, filed September 29, 1944, which is incorporatedherein by reference as though fully set forth herein.

Comparison may be made with the circuit per Fig. 13 which isfunctionally the same. It is again assumed that line only is used andthat it is arranged for polarential operation with polar sending. Forthis condition, the line switch is in position 1. The local switch isoperated to position 5. The internal connections of the repeater perFig. 1 and Fig. 2 for this option are the same as described above forthe right-hand repeater in Fig. 12 except that the connection fromterminal 0 to relay winding 215a is not used. Local terminal 8 and localterminal 9 of the repeater per Fig. 2 herein are connected to a pair ofterminals for a particular line such as line A in the electronicregenerative repeater. It is particularly pointed out that theelectronic regenerative repeater is arranged to serve two repeaters suchas the repeater per combined Fig. 1

and Fig. 2 herein, simultaneously. Reference to Fig. 13 indicates themanner in which other repeaters may be connected to the singleelectronic regenerative repeater. The circuit in the electronicregenerative repeater extends from a particular terminal associated witha particular line through variable resistance |30|, the armature andmarking contact of relay |302, winding of relay |303 and conductor |304to the corresponding line terminal 2 from which point it is connected bymeans of conductor |305 to local terminal 8 of the repeater herein.Terminal is connected to local terminal 9 of the repeater herein bymeans of external conductor |306. Relays |302 and |303 of Fig. 13 hereincorrespond to relays |3 and I4 of Fig. l of the application, per SerialNo. 556,352 mentioned above. The corresponding relays to which thesecond repeater would be connected are relays 33 and 34 of theelectronic regenerative repeater. Connections from positive and negativebattery to the marking and spacing contacts of relays 215 and 216 arethe same as have been traced heretofore.

The `circuit for manual telegraph set operation of the repeater hereinwill now be traced. Comparison may be made with the circuit per Fig. 14which is functionally the same. For this condition, it will be againassumed that line only is used and that it is arranged for polarentialoperation ,with polar sending. The local switch is operated toposition 1. The printer transmitter plug and the printer receiver plugare disconnected from their corresponding jacks. The plugassociatedvwith head set 289 is inserted in the head set jack closingthe normally open contact 285.

For this condition, a circuit may be traced from the head set 289 at theupper right of Fig. 2, through sleeve 288 of the associated plug, sleeve282 of the head set jack, condenser 283, conductor 340, induc'tance 295,conductor 345, contact 30| of manual telegraph key 300, closed contact292 of the printer transmitter jack, inductance 294, conductor 330,conductor 321, conductor 328, contact 1 of unit |6, projection 53,segment 33, contact I2, conductor 20 I, which extends into Fig. 1,contact 94 and armature of relay 92, conductor |98, conductor 226, whichextends into Fig. 2, contact 6 of unit I6, segment 32, projection 52,contact conductor 358, conductor 354, conductor 251, conductor 2|1,which extends into Fig. 1, and conductor |50 to negative battery. Fromthe opposite terminal of the head set 289 a circuit may be tracedthrough the tip 281 of the head set plug, tip 286 of the head set Ajack, resistance 28|, variable resistance 280, conductor 36|, conductor315, which connects in parallel to open spacing contact 213 of relay215, and marking contact 218 of relay 216, through contact 218 andarmature of relay 216, conductor 33|, conductor 221, which extends intoFig. 1, conductor 200, conductor |99, contact of unit I2, projection 31,segment 20, contact 4, conductor 220, relay winding 92a, conductor 222,contact I2 of unit |2, segment 22, projection 39, contact 9, conductor|05, variable resistance 18, conductor ||0, resistance 85, conductor l,variable resistance 19, conductor |01, conductor |02, inductances 1| and61 and conductor to terminal 3 associated with line Another circuitextends from the tip conductor of the head set jack through closed makecontact 285, and neon lamp 284, to the left-hand terminal of condenser283. A circuit may also be traced from positive battery in Fig. 1through conductor 5|, which extends into Fig. 2, conductor 246,conductor 248, resistance 249, contact l of unit |9,

. projection 58, segment 4|, contact 6 of unit |9,

conductor 324, relay winding 215a, conductor 356, relay winding 216a,conductor 352, contact 6 of unit |1, segment 34, projection 54, contactI, conductor 350 and conductor 334 to the left-hand terminal ofcondenser 283.

The contacts of key 300 are shunted by condenser 299.

Positive and negative battery are connected to the marking and spacingcontacts of relays 215 and 216 as heretofore traced.

Radio suppression lters 293, 306 and 3 2 which have inductance in serieswith the printer leads and external conductor leads 8, 9 and |0 andcapacitance shunted between the leads and ground suppress radiofrequency currents generated in the repeater from being radiated by theleads to the printer and other external connections.

INTRODUCTORY DESCRIPTION or THEORETICAL OPER- ATION 0F LINE SIDE 0FREPEATER Introductory description ofk polarential, operation Althoughpolarential operationis well known in the art, and may be understoodfrom reference to the Cramer patent mentioned above,` it will bedescribed in a general Wayv preliminary to a description of theoperation of the polarential line options of4 the present repeater. Itis particularly pointed out that the polarential circuits'for theCramer-patentand of" the explanatory'Figure 15 herein have beenrnodiiiedin accordancewith the invention herein to` permit theirapplication to linesA oflonger span than hasheretofore been possible.

Fundamentally, a circuit operating ony apelar;- ential` basis usesApolary transmission in one direction andfdiflerential transmission intheother direction. These two termsv have been combined to form the wordpolarential'- Fig. 15is a. theoreticalschematic of polarentialoperation. Ina polar transmission system, the marking and spacing lineVcurrents transmitted from' one station are of the samemagnitudeand owinopposite directions and hence, thel receiving; relay at theotherstation, operates'on reversals of line current and requires nolocal bias circuit.. In adifferential transmission system, the markingand spacing'lineY currents. are inthe same direction but' different inAmagnitude and this difference as applied to the polarential method`ofoperation requires a spacingycurrent about 21/2 times-'the markingcurrent. Since the spacing current is in the same direction as themarking` current. a repeater receiving marking and spacing currentsowing in thev same. direction. requiresv a local biasing circuit on the.receiving relay. yBy xing this localA biasing circuit in amarkingdirection at halfr the sum of' the received marking and spacingllinecurrents,.and poling the line Windingofithe receiving relay spacing, thenet eiect on'the' armature of the receiving relay is` equivalent topolar transmission. To get*y thisv equiya lent of polar transmission inbothl directions on one telegraph channel, the opposite ends of apolarential circuit are made dissimilar as regards the connections ofthe sending and receiving relay circuits andV the operatingvoltagesapplied to the line. One end of' the circuit applies nega.- tiveandI positive polarity of' the. same. value. while sending. for themarking and spacing conditions respectively andthis is known asthepolar. send.- ing end of the circuit. The other endof the circuitapplies` groundfor marking. and. positive polarity for spacing and isknown as thediierential sending end of the circuit. For, thetransmissionof a spacing signal fromthediierential sending end thepositive battery at the difieren.- tialsending end'r isin serieswithnegatiyebattery connected normally to the line, at. thespolarend.Thus the magnitude of the, voltage is approxi mately 21/19-` times thevalueV of the negativebat.- tery at the. polar end. Assuming, a.directionof flow of current from positive to negative it. will beobserved that in transmitting. from. the dif.- ierential. sending endAthe direction, oi the ow of' current for marking signals is fromthe.differential end to the opposite. end. For. the trans-` ReferencetoF-ig: 151 shows-:the'i-arrangementiofza l type B polarentiallineiorf aparticular embodi'f irren-t.4 Inlv Eig.: 15., thepolarv sendingfstation. is at the. left; Batteries: of equal.' potential. and oppositepolarity', positive and negative 75: volts, are connected tothe line:throughv the operation. ci relay |511 l for. transmissionrom the 'polarvsendiingend. At: the opposite end. of the. circuit the armature ofisending relay llif is connected to ground. Eor'fthe` transmission fromthe diieren.- tial sending end ground. is connected` to.` theline formarkingand the current is assumedl to ow from ground to negative batteryat the distant end. When relay: |5041 is operated for a spacing signalpositive L15-volt battery isV connectedl to the polarential. endof the.line in series with negative, battery at the. distant end. The.V sum. ofthe battery voltage. is about 2% times the voltage impressed onthe linefor themarking condition.

For transmission from the polar transmitting end,.Fig. 15A represents.the magnitude of the marking and spacing signals. received from.v relay|51114 by relay- 1.503 for dry and Wet conditions. For a. dry liner themagnitude .of thelcurrents4 for marking and spacing are greatest andthey. are of, course equal.

The. magnitudes lol4 the receiving. marking, and spacing currents are'.decreased for diierent. degrees of wetness but they remain equal andunbiased; signalsV are. received. by relayVv |503.. No biasing1 windingis required` therefore on. receiving4 relay i503..

For transmission from the.. differential trans.- mittingendlig. 15Brepresents the.. magnitudes of." the current received` by relay |5112.from. relay 1.50.4'. ItV indicates. that... the magnitude: of4 themarking and` spacing. signals are affected. equally for differentdegrees of wetness.. Themagnitude of the.. spacing, current is greatestandl the mag.- nitude. of` themarkingcurrent is leastfor the .drycondition.. The, magnitude. of.' the marking; cur.- rent is.. decreasedby the same amount. that the magnitudeA of. the, spacing. current isyincreased for Wetv conditions. The biasing, current. in, the receiving,relay |502 is fixed at half the-sum of the markingl andjspacing currentsfor the. dry condition.u As. the valuesoithe current received by relayI15I2 change for. diierent degreesoi wetness the, difference. betweenthe biasing current and the marking and spacing currents remains equalone tor another.

Thus. for values of 46 milliamperesmarking current and 18 milliamperesspacing current obtainedfor the` dry condition for the voltage employedinthe particular embodiment of' Fig. 15 and for a particular lineimpedance, the biasing current may Icev permanently established at' 32milliamperes andthe received signals will be effectivelypolar signalsnot withstanding changes incurrentA magnitudes due to varyingl leakancefor diierent degrees of wetness.

Introductory description of two-path polar operation;

Refer now to Figs; 16, 16A=and16Bwhichshow the theoretical operationoflthe line vsidey of'A the circuit for. the: two-path polar line option;This system. of, operation is` also; well known in. the art.. Itzis;particularly-pointed out that in the presentinvention: thetheoretical.twofpath. polar system has been modied in a manner. `to-` be: describedhereinafter.

In two-path polar operation a separate channel is required fortransmitting in each direction. Reference to Fig. 16 shows that voltagesof'equal magnitudes, in this embodiment 75 volts, and of oppositepolarities are impressed on the line at the transmitting end for markingand spacing signals. Fig 16A indicates that, when the transmission isfrom relay I60|, relay |602 receives signal currents of' equalmagnitudes for marking and spacing whether the line is Wet or dry.

When transmission is in the opposite direction, or from relay |603 torelay |604, over the second channel, the signals received by relay |604are, of course, the same as shown in Fig. 16A for the opposite directionsince the voltages are the same.

Eject of long spans Reference to Fig. 15 shows that there is areceivingrelay having a winding in series with the single line at eachterminal. If the line has a high capacity to ground the receiving relaysare affected by a phenomenon well known in the art as kick o. By this ismeant the false operation of the receiving relay due to current surgescaused by the discharge of the line capacity back through the winding ofthe receiving relay when the transmitting relay at the same station issending.

The longer the line the greater its total capacity and the greater themagnitude of the current surge through the winding of the receivingrelay. The repeater .of the invention herein is designed to function on50 to 'l5-mile lines of high to kick ofi effect have heretofore beensatisfactorily operated. Various anti-kick off features are presentlyknown in the art but none of the presently known arrangements iseifective to prevent kick off on lines having spans of such length asthose on which it is contemplated the present repeater will be applied.The anti-kick oir feature of the present invention makes possible theeffective operation of direct current repeaters such as those shown inFig. 15 on spans up to 75 miles in length as a normal procedure andunder favorable conditions Where the distributed capacity is less it iseffective on spans of considerably greater length. This is importantparticularly in military service, where, due to many well understoodcircumstances, satisfactory operation on lines of long span is ofparamount importance.

DETAILED DESCRIPTION or OPERATION F REPEATER Repeater line circuitoperation- General In the case of polarential, polar sending, and two-path polar operation, the transmission branch of the present repeateris arranged for double commutation to permit sending negative andpositive battery from a single non-grounded power supply. Two sendingrelays 215 and 216 in Figs. 1 and 2 are needed for this type oftransmitting branch. The reversal of polarity takes place across apotentiometer Vcircuit comprising resistances 212 and 365 which inthepresent embodiment provides 75 volts for marking and 75 volts forspacing in polarential polar sending and two-path polar transmission.

The protector blocks serve to protect the equipment from surges inductedinto the line by lightning or nearby power lines. Filter is a radiosuppression lter. Retard coil 1| is a telephone noise killer coil.

Line side of repeater operating polarential, polar sending Refer to Fig.3.

The adjust line current course switch 60 in Fig. 1 controls seriesresistance and shunted capacity to provide wave shaping and at the sametime an approximate adjustment of the line current. The nal value ofline current is obtained by turning the adjust line current nepotentiometer 10.

The circuit is shown in the marking condition. The armatures of relaysS1 and S2 are operated, either to the right or left, in unison undercontrol o-f a circuit assumed to be connected to the right-hand side ofthe repeater. 'Ihe line is terminated at the distant office in arepeater arranged as per Fig. 4 for differential sending. The circuit isarranged for half duplex operation, that is, communication is possiblein only one direction or the other at a particular time. t the distantend, Fig. 4, line I is terminated in ground. The li-ne circuit per Fig.3 has been traced in the foregoing from terminal 3 to the armature ofrelay 216. When in the idle or marking condition the armatures or relays215 and 216 are both actuated to the left, under the influence of thelocal side of the circuit, to engage with their marking contacts asshown. The two resistances 365 and 212 are connected across the positiveand negative terminals of the -volt -power circuit so as to cut down thevoltage connected to the line in this embodiment to '75 volts. Theoperation of relays 215 and 216 in unison reverses the ground connectionto one side or other of the output circuit of the power supply solas tochange the polarity while maintaining the voltage constant at 75 volts.Thus, for the marking condition indicated, ground is connected to thejunction between resistances 212 and 365 and a circuit may be tracedfrom ground through the armature and left-hand contact 214 of relay 215,resistance 212 and the armature and left-hand contact 211 of relay 216,connecting negative 'T5-volt battery to the path which has been tracedthrough the top winding of receiving relay 92 through conductor I toterminal 3, from which point it extends through a line to a polarentialrepeater arranged as in Fig. 4 herein, to ground connected to themarking contact of a relay corresponding to relay 216 in Fig. 4. For thespacing condition, the armatures of relays 215 and 216 are operated totheir right-hand contacts. For this condition ground is connected to thenegative terminal of the power circuit and the circuit may be tracedfrom ground through the armature and right-hand or spacing contact 213of relay 215. The positive side of the power supply may be tracedthrough resistance 365, resistance 212 to spacing contact 218 of relay216. This connects positive 'l5-volt battery in this embodiment to theline. f

The circuit through line winding 02a for the marking condition forsignaling over the circuit is in such a direction as to tend to operatethe armature of relay 92 in Fig. 3 to engage with its spacing rcontact94. The effect of the current in the biasing winding 9217, which remainsfixed in direction, tends to operate the armature of relay 92 to itsmarking contact and this latter effect is greater than the oppositeeiect of the line winding. The armature of receiving relay 92 is,therefore, maintained in engagement with its marking contact.

When a spacing signal is transmitted from the polar sending end, thedirection of the current in line winding 92a is changed so that theeiect augments the effect of the bias current in the winding 92h and thearmature of relay 92 is held more rmly to its marking contact.

